Devices and methods for dynamic broadcast

ABSTRACT

A dynamic broadcast system and a spectrum management device for use in a dynamic broadcast system. A dynamic white space database unit stores and dynamically updates a dynamic white space database of frequency resources that are assigned for broadcasting broadcast content but can locally not be used for broadcasting. One or more white space devices can access the frequency resources included in the dynamic white space database. A spectrum server dynamically manages the frequency resources included in the dynamic white space database for access by the one or more white space devices.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of application Ser. No.13/856,794, filed Apr. 4, 2013, now pending which claims priority toEuropean Application 12 168 678.6, filed on May 21, 2012, the contentsof both which are incorporated herein by reference in their entireties.

BACKGROUND Field of the Disclosure

The present disclosure relates to dynamic broadcast. In particular, thepresent disclosure relates to a terminal and a corresponding receivingmethod, a dynamic broadcast system and method, a controller device, acontrol method and a computer readable non-transitory medium.

Description of Related Art

The scarce terrestrial frequency spectrum is an important factor for thedevelopment of wireless communication. Nowadays broadcast services takeup a significant part of the frequencies in the (e.g. UHF or VHF)broadcast bands, which are ideal for in-house reception. Thanks todigitization, the spectrum usage efficiency of broadcast services hasbeen increased largely compared to the times of analog. However, thenetwork operation remains still static, i.e. the transmission parametersare fixed and invariable, transmitter power is constant, and servicesare delivered in pre-determined channels. Such traditional broadcastnetwork has very low requirements on the receivers. Neither a feedbackchannel nor a content storage device is necessitated, and a channel scanprocess is usually only needed when the terminal device is powered onfor the first time, since the transmission parameters for each TVchannel will be stored for later tune-in.

Consumer electronics industry develops rapidly, and user terminals arebecoming more and more powerful. Recently, a trend in the field ofconsumer TV is the development of “hybrid user terminals”” which canacquire media content via broadband networks, such as xDSL, DOCSIS orsatellite communication links and, eventually, even via wirelessInternet networks (e.g. via a Long Term Evolution (LTE) network) orother wireless data networks in addition to traditional broadcastnetworks. Although such receivers allow the seamless access to bothInternet and broadcast content, there are almost no inter-workingfeatures between the two delivery means. Another notable point is thatmore and more TVs and Set-top-boxes (STB) are equipped with huge storagedevices and this is essential for the time-shifted consumption of mediacontent. The content storage can be controlled normally by the user or ascheduler to build personal television channels, but still is neithercontrolled by either network nor influences what happens in the network.In certain cases, providers of Pay-TV-services have started topre-download content onto the storage devices in order to provideviewers with more choice of programs.

These new capabilities of user terminals, namely the available broadbandnetwork access and a storage device with reasonable capacity, may notonly be utilized to enhance the user experience, but also to reduce theTV programs delivery cost and to increase both the efficiency ofspectrum usage and the energy efficiency of the whole system.

Firstly, taking advantage of the presence of the second delivery means(the broadband network), the ingrained TV viewing habits can beexploited to optimize the TV content distribution. Broadcast is optimalfor a massive audience, since the network operation cost is almostindependent of the size of its audience for a given coverage area, whichindicates that the more users it serves, the lower the cost for theindividual user remains. In contrast, the cost of broadband deliveryincreases generally as the viewer number gets larger and in case ofunicast the relation is nearly linear. This implies that for thoseevents which have a small audience, delivery via a broadband network maybe more cost-efficient.

Moreover, managed by the user terminal, the storage device is able tostore the contents which are planned to be repeated by the broadcasterin the following 14 days or so and which the user is predicted to havestrong interest to watch. In this way the on-air viewer numbers ofrepeated TV content can be reduced significantly and the skewness of thechannel popularity distribution is considerably reinforced. Suppose thatthe remaining number of on-air viewers falls below a pre-definedthreshold, the content then should be reallocated to the broadbandchannel, thereby freeing capacity in the broadcast channels or even thespectrum.

Further, due to the fact that TV viewer numbers vary significantlyduring a day, the freed capacity has also a strong time-dependency. Inthe prime-time hours freed data rates will be much less than e.g. overnight. To make a better use of the spectrum a new delivery strategy isdefined, which uses the broadcast capacity over night to pre-transmitsome of the TV content to user terminals. At a pre-signaled broadcasttime these terminals can then play back the content from their storagedevice directly. As a result, the number of terminals which have toreceive the live broadcast will be lowered and eventually this livecontent may also be moved to a broadband channel. Similarly, thepre-transmission can also be placed in the broadband channel duringlow-traffic hours, so the load of the broadband network during day-timecan be reduced.

The freed capacity is extremely valuable for both broadcasters and otherwireless communication network operators. The following possible usagescan be considered for instance: Deliver more broadcast services; adjustthe transmission parameters to a more robust mode, with the purpose thatthe power consumption of the transmitter can be reduced; and shut downcertain broadcast channels temporally and make the frequencies availableto secondary wireless service providers for a certain time period.

The development of new wireless communication systems is oftenrestricted by a lack of available frequency spectrum. On the other hand,many frequency bands allocated to specific technologies are oftenunderutilized. TV White Spaces (TVWS) are frequency bands which areallocated to terrestrial broadcasting systems, but are locally notusable by broadcast network operators due to interference planning ormissing broadcasting infrastructure. Regulation authorities,standardization bodies and research institutes as well as industry areseeking ways to make use of these valuable frequency resources forsecondary wireless communication (secondary users, generally calledwhite space devices WSDs).

There are some restrictions on the efficient use of TVWS spectrum. Onthe one hand, primary spectrum users (primary users, predominantlyterrestrial broadcast networks), have to be protected against harmfulinterference from secondary users operating in the same frequency bands.On the other hand, overly stringent (conservative) TVWS usagepermissions can significantly reduce TVWS availability. Furthermore,TVWS availability may vary from location to location, typically offeringless capacity for high population density areas.

A known technology for managing TVWS spectrum access, as for instancestated in the ECC report 159, is the use of geolocation databases (orwhite space databases). All relevant spectrum usage informationincluding primary transmitter locations, terrain and propagationcharacteristics and transmission powers have to be stored in thesedatabases. WSDs must know their position and must consult the whitespace database before they are put into operation. By this query, a WSDcan find out usable frequency bands and maximum permitted transmitpowers at its location. However, white space databases cannot overcomethe issue of TVWS spectrum not being available in a certain location,nor can they handle the potential interference to broadcast receivers.

The “background” description provided herein is for the purpose ofgenerally presenting the context of the disclosure. Work of thepresently named inventor(s), to the extent it is described in thisbackground section, as well as aspects of the description which may nototherwise qualify as prior art at the time of filing, are neitherexpressly or impliedly admitted as prior art against the presentdisclosure.

SUMMARY

It is an object of the present disclosure to provide devices and methodsfor use in dynamic broadcast as well as a dynamic broadcast system andmethod that enable an efficient, automatic and flexible transmission ofcontent via a broadcast network and a broadband network.

According to an aspect of the present disclosure there is provided adynamic broadcast system comprising

-   -   a broadcast transmitter configured to broadcast content via a        broadcast network,    -   a broadband server configured to provide content via a broadband        network,    -   a controller that dynamically controls transmission parameters,        transmission times and transmission paths used for broadcasting        content via said broadcast network and providing content via        said broadband network,    -   a dynamic white space database unit that stores and dynamically        updates a dynamic white space database of frequency resources,        which are assigned for broadcasting broadcast content but can        locally not be used for broadcasting,    -   a decision unit that dynamically decides transmission        parameters, transmission times and transmission paths used for        broadcasting and providing content,    -   one or more white space devices that can make use of frequency        resources, which are comprised in the dynamic white space        database, and    -   a spectrum server that dynamically manages frequency resources,        which are comprised in the dynamic white space database, for use        by the one or more white space devices.

According to another aspect there is provided a spectrum managementdevice for use in a dynamic broadcast system for providing content toterminals, said spectrum management device comprising:

-   -   a dynamic white space database unit that stores and dynamically        updates a dynamic white space database of frequency resources,        which are assigned for broadcasting broadcast content but can        locally not be used for broadcasting,    -   a spectrum server that dynamically manages frequency resources,        which are comprised in the dynamic white space database, for use        by the one or more white space devices that can make use of        frequency resources, which are comprised in the dynamic white        space database.

According to still further aspects corresponding methods, including adynamic broadcast method and a spectrum management method as well as acomputer program and a computer readable non-transitory medium havinginstructions stored thereon which, when carried out on a computer, causethe computer to perform the steps of the spectrum management methodaccording to the present disclosure are provided.

Embodiments of the disclosure are defined in the dependent claims. Itshall be understood that the claimed devices, system, methods, computerprogram and computer readable medium have similar and/or identicalpreferred embodiments as the claimed terminal and the claimed dynamicbroadcast system and as defined in the dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the disclosure and many of the attendantadvantages thereof will be readily obtained as the same becomes betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawings, wherein:

FIG. 1 shows a schematic diagram of the general layout of a dynamicbroadcast system;

FIG. 2 shows a simplified schematic diagram of a dynamic broadcastsystem;

FIG. 3 shows a schematic diagram of a terminal according to the presentdisclosure;

FIG. 4 shows a more detailed schematic diagram of an embodiment of aterminal device according to the present disclosure;

FIG. 5 shows a schematic diagram of a demonstrative environment;

FIG. 6 shows a diagram of NiS operations feasible in the demonstrativeenvironment of FIG. 5;

FIG. 7 shows a schematic diagram of another embodiment of a terminal;

FIG. 8 shows a schematic diagram of a network management unit of dynamicbroadcast system;

FIG. 9 shows a schematic diagram of another embodiment of a terminal;

FIG. 10 shows a state diagram of an active receiver and the transitionsresulting from network-initiated switching;

FIG. 11 shows a schematic diagram of another embodiment of a terminal;

FIG. 12 shows a diagram of the data rate dependence of FIFO buffer sizeduring 60 s of continuous TS playback without NiS for a delay timeT_(D)=3.5 s,

FIG. 13 shows a diagram of the rate dependence of the FIFO buffer sizeduring 60 s of continuous TS playback including 3 NiS operations for adelay time T_(D)=3.5 s;

FIG. 14 shows a schematic diagram of another embodiment of a dynamicbroadcast system including a dynamic white space database and a spectrumserver; and

FIG. 15 shows a flowchart of an embodiment of the communication betweendevices using the same frequency resources and the spectrum server inthe dynamic broadcast system shown in FIG. 14.

DESCRIPTION OF THE EMBODIMENTS

The present disclosure supports the provision of true convergence andinteroperability of broadband and broadcast networks leading to asignificant extension of spectrum usable for wireless broadband systems,preferably inside the UHF frequency band while not jeopardizing thetraditional quality of service and quality of experience known fromterrestrial broadcasting. By use of the present disclosure thetime-varying demand for wireless broadband services can be accommodatedin that at times of the day when the less popular TV programs orprograms that are repeats of programs first delivered during the lastday or days are being played out, more spectrum can be released by thebroadcast network operators than during the evenings when the morepopular programs are broadcasted. A kind of water filling is madepossible through this approach in which the spectrum demands of thewireless broadband and the broadcast networks are mutually optimized.

The present disclosure particularly provides for management/controlelements that dynamically control the transmission, storage and use ofcontent via the broadcast network and the broadband network. Inparticular, the transmission parameters, transmission times andtransmission paths used for broadcasting content via the broadcastnetwork and for providing content via the broadband network aredynamically controlled. Through said control the multiplexconfigurations of the transmission of content (in particular over thebroadcast network) can be dynamically controlled including theallocation of content to multiplex content data streams transmitted overthe broadcast network or the broadband network.

Further, the use of adequate signaling information or other data ispreferably proposed for ensuring seamless presentations of content tothe user, automatic control and an efficient use of the availableresources, whereby it is provided that any switching between entitiesused for transmission of content is not realized by a user watching apresentation of content. Thus, the present disclosure supports toprovide benefits to all parties in the business chain as follows.

For frequency regulators a possibility to respond to the demand ofoperators of wireless broadband devices for more spectrum is providedwithout having to come into the kind of conflict with the broadcastnetwork operators that would result from a Digital Dividend. At the sametime, the workload required to resolve problems caused by interferenceof the traditional White Spaces will be significantly reduced.

Operators of wireless broadband networks will gain more spectrum fortheir services with a much reduced probability of problems resultingfrom interference between their networks and broadcast TV networks. Theywill be able to use higher transmitter power levels in their networksand the amount of spectrum available to them can—in co-ordination withthe operator of the broadcast networks—be adapted to their capacityneeds.

Operators of broadcast networks will not lose spectrum through a DigitalDividend completely but will be able to keep control of the spectrumavailable to their services—in coordination with the operator of thewireless broadband networks. In addition, the present disclosureprovides them the possibility to save energy and cost of operation.Operators of broadcast networks might e.g. choose to lease thedynamically freed spectrum to other users. The TV viewers will notexperience any loss in Quality of Experience in comparison totraditional broadcasting and at the same time retain more choice ofprograms which would have been restricted through Digital Dividends.

Contrary to terminals, such as a Web-TV, having a broadcast receiver forreceiving regular broadcast and a broadband receiver for receivingcontent via a broadband network, terminals according to the presentdisclosure comprise a management unit that controls which content shallbe received via which network and that further controls from whichsource (i.e. the live broadcast reception, a live broadband reception orthe storage unit) content to provide to the output unit, e.g. forpresentation on a screen. This is generally done in a manner that is notnoticed by the user who shall generally not realize any difference tothe conventional way of consuming media content (in particular theconventional way of watching TV). In conventional terminals likeWeb-TVs, the user, in contrast, has to actively decide where to getcontent from and between which sources to switch.

As explained above dynamic broadcast is a system in which TV contentdelivery can equally be realized over both, a terrestrial broadcastnetwork and a broadband network. User terminals are connected to bothnetworks and are additionally equipped with a local storage device. Bymaking use of this storage device, TV content which does not requirelive transmission can be delivered “non-live” in advance, which impliesa remote management of the user terminals by a network management unit.In dynamic broadcast the content delivery network, the delivery time,the multiplex configurations of the terrestrial broadcast network andall transmission parameters are configured dynamically, in order toachieve an optimal operating state.

Besides having the potential to reduce transmission costs, dynamicbroadcast can optimize the spectral efficiency within the terrestrial TVbands. For certain periods of time, the transmission power in abroadcast channel can be reduced, or the channel can be switched offcompletely, thereby increasing TVWS spectrum, which can be used forsecondary wireless communication. These additional dynamic white spacechannels (hereinafter also called dynamic TVWS channels) are especiallyuseful in regions with low TVWS availability. Furthermore, these dynamicTVWS are signaled to the secondary users, which no longer have to relyon mere assumptions of usable frequency bands. White space spectrum cantherefore be made available for secondary users in abroadcaster-controlled way, which comprises the control of potentialinterference by secondary users.

The management of the frequency resources (in particular the grant andrevocation of frequency resources) required for the broadcasttransmissions is carried out by the dynamic broadcast network managementunit (also called decision logic). In contrast to conventional staticbroadcasting systems, TVWS in dynamic broadcast become time-variant.Spectrum requests from WSDs can be included in the decisions of thedecision logic, which can adapt the dynamic broadcast network parametersaccording to their needs. Therefore, an optimal spectrum utilizationscheme can be achieved, taking the time-variant spectrum demand bysecondary users into account.

For the management of dynamic TVWS and for the communication linkbetween the dynamic broadcast network and the secondary users, thepresent disclosure provides a dynamic white space database solution. Incontrast to other white space databases, the dynamic white spacedatabase includes the broadcast network operator as the primary user,who has to register in the database. Dynamic spectrum usage of theprimary user is taken into account. In order to retain the primarystatus of the dynamic broadcast network, a prioritization of allspectrum users and a well defined communication protocol areimplemented. In this way it is ensured that even if WSDs are making useof dynamic TVWS, the dynamic broadcast network operator can retrievethese frequency resources at any time. Therefore, it is possible to makeadditional TVWS available for secondary use, while making sure, that theprimary user retains control over its allocated spectrum. A spectrumserver is defined, which is responsible for the management of thedynamic white space database and the communication protocol.

In the context of the present disclosure the term “white space device”(and its abbreviation “WSD”) may be understood in a broad sense coveringall kinds of devices that can generally make use of a frequency resourcethat is comprised in the dynamic white space database. Said one or moredynamic white space devices may thus comprise one or more of a terminal,a broadband server and/or a service provider providing a service in apredetermined area, in particular as a wireless network serviceprovider, a sensor network provider, a security network serviceprovider, an ad-hoc network and/or a control system of wireless devicessuch as wireless audio systems, microphones and loudspeakers. Furtherexamples are possible.

It is to be understood that both the foregoing general description ofthe present disclosure and the following detailed description areexemplary, but are not restrictive, of the present disclosure.

Referring now to the drawings, wherein like reference numerals designateidentical or corresponding parts throughout the several views, FIG. 1shows a schematic diagram of a dynamic broadcast system 1. The systeminvolves a broadcast (BC) network, a broadband network (BB), hybridbroadcast broadband (HBB) terminals and other wireless communicationnetworks. Their cooperation is managed by the dynamic broadcast network.The functions of the blocks shown in FIG. 1 are explained in thefollowing.

First, the packaging of media content unit 12 is described. The TVcontent is provided by broadcasters 10 and is segmented into Real-Time(RT) and Non-Real-Time (NRT) events. For real-time events, (certainelements of) news programs for instance, their content becomes availableonly at the announced on-air time, so they have to be delivered live;while for non-real-time events, like movies, music, drama etc., theircontent may be available in advance, so they can be pre-downloaded. Withpre-download (broadcast or broadband) network capacity can be used forinstance over night, when capacity has been identified to be available,whereas during daytime and in the evening network capacity will be freedfor other uses. The choice of content that can be pre-downloaded will bebased on rules used in a decision logic 14. These rules will begenerated from usage patterns of viewers derived from informationavailable over the broadband network. In conjunction with other measuresthe download of such material will take place as network capacitybecomes available—either over the broadcast or the broadband network. Aprogram schedule therefore should be created that indicates whichcontent comes over the air in real-time and which content can be playedfrom the storage device in the user terminal.

Next, a monitoring and signaling unit 16 is described. To optimize thenetwork operation, knowledge about actual network usage is important.Two kinds of information should hence be collected from HBB terminals 18(also called “terminals”, “user terminals” or “receivers” hereinafter)and transmitted to the decision logic 14 through broadband connection.The first kind of information is about whether or not programs or piecesof media content are used and by how many people. This popularity can beestimated by monitoring the watching activities of some or all users, asdone in today's IPTV networks. Knowing the accurate popularity and usagepattern of the media content can help the decision logic 14 determiningwhich content should be delivered via the broadband network and/orpre-downloaded as mentioned above. The second kind of information isabout the momentary technical Quality of Service (QoS) of thetransmission links. This can be obtained with integrated measuringdevices in HBB terminals 18. With information about the actual signalquality, the decision logic 14 can manage the network most efficiently.

The signaling which delivers data to the HBB terminals 18 will provideinformation about content items presented for ‘delivery in advance’(also called ‘offline delivery, i.e. delivery in advance of the officialbroadcast time), the time of the broadcast transmission and/or the timeof play out over the broadband network. It will include a programschedule and it will deliver information about the various parametersselected by the dynamic multiplexing and a joint control unit 20. Thesignaling information can be transmitted via both networks and in bothpush and pull modes, so that the HBB terminals 14 can get the currentnetwork information even if it is just switched on for the first time.

The decision logic 14 is in charge of the management of the wholenetwork and it aims to keep the operation at a minimal cost whileassuring required QoS. Facilitated with the monitoring reports from theHBB terminals 18, and based on additional business rules, costfunctions, realistic constraints etc. the decision logic 14 may changethe packaging of real-time and non-real-time events, or command are-multiplexing of the transport streams in broadcast and broadbandchannels or adjust of the transmission parameters and transmitter power.Before the decision logic 14 has made any changes to the previousprogram schedule or network settings, it should acknowledge all HBBterminals 18 about the modification through signaling.

Next, a multiplexing and content distribution unit 22 is described. Theflexible distribution of media content through broadcast and broadbandnetwork requires content items and complete or partial audio, data andvideo programs to be multiplexed dynamically. In consequence, the formerfixed mapping between transmission parameters and TV programs has to beeliminated. Information about such re-multiplexing should be signaled tothe HBB terminals 18, so that they are able to follow the changes. Bythe reason that the popularity of the different TV programs in onetransport stream changes continuously, re-multiplexing may take placeonline, which means some content being transmitted may be reallocated inother physical channels or still in the current channel but with newtransmission parameters. All these actions should be carried out in away unnoticeable by the users.

Next, the joint control unit 20 for control of transmission parametersis described. In traditional digital broadcast systems the modulation ofthe transmitted signal and the degree of Forward Error Correction (FEC)used are decided once and they then stay stable. The transmitter poweris selected according to the coverage requirements of the network. Interrestrial networks, the coverage area is defined by the aforementionedparameters and in addition by the coverage pattern determined by thetransmit antenna. This static network planning leads to inefficientusage of the valuable spectrum, because strong time-variant factors likechannel popularity and user terminals receiving conditions have not beentaken into consideration.

Dynamic multiplexing can reduce the useful data rate transmitted on aspecific channel if the multiplex on that channel is not fully loadedwith program items at the moment. Initiated by the decision logic 14 thejoint control unit 20 will then change the FEC settings and/or modifythe modulation scheme used on that channel. This will result in anenhanced robustness of the signal which in consequence will allow thetransmitter power to be adapted thus reducing the power density—and thecost of transmission. This creates economical benefits, as well asecological benefits, since the exposure to radiation and carbon emissionwill be reduced as a consequence of the lowered transmitter power. Inanother case, it shall be supposed that signaling provided from userterminals to the broadcast network including information about technicalparameters of the received signal in networks indicate abetter-than-required or worse-than-required signal quality as a resultof changes in man-made noise (i.e. noise generated by any devices usedby anybody in the environment)—which has been found to fluctuate greatlyand periodically over time—or due to changes in weather conditions.Initiated by the decision logic 14 the joint control unit 20 will modifythe parameters (FEC, modulation, transmitter power) in order toaccommodate broadcast QoS at a minimum cost. In addition, the jointcontrol unit 20—in negotiation with dynamic multiplexing via thedecision logic 14—will initiate the re-configuration of multiplexes suchthat the data rate transmitted in heavily disturbed channels will bereduced and the robustness of the signal enhanced as required.

In the HBB terminal 18 some content will have to be stored “off-line”upon receipt of the appropriate downstream signaling and besides, whichcontent to store should also be decided by the HBB terminal 18.Therefore it should be capable of predicting user's preferences, storingrelevant TV content automatically and managing the stored contentdynamically. To accomplish this, a recommender system should beimplemented in the HBB terminal 18. On the other hand some content willbe made available via the co-operating broadband network. The HBBterminal 18 will receive a program schedule, and a delivery networkindicator which indicate for which period of time and how often thisstored content is to be used instead of content that in traditionalbroadcasting would be received live. In addition it will be informed viawhich of the co-operating networks content will be delivered. Thereceived content from different networks should be managed properly bythe HBB terminal 18. Content items are often interrelated. This isobviously true for audio and video but in addition, a plethora of dataservices like software applications are created by the content ownersthat will have to be available in the terminal 18 and started, paused orcancelled in relation to the audio and video content. Additionaldownstream signaling information embedded in the broadcast stream isreceived by the HBB terminal 18, which indicates the dynamic multiplexconfigurations and the parameters selected by joint control. Upstreamsignaling will be generated in HBB terminals 18 for transmission on thebroadband network. The user terminal 18 thus becomes an active componentof the dynamic broadcast network instead of being a passive device as intraditional broadcasting.

Spectrum freed by dynamic broadcast can be offered to secondary wirelessnetworks, like Cellular (LTE), Wi-Fi, etc. for a certain period of time.To avoid interference, usage of the new “white space” created by dynamicbroadcast should be coordinated through resource signaling which is anoutput of the dynamic broadcast system 1 and informs wireless networkoperators about the dynamically chosen parameters of the broadcastnetwork. It includes also information about the period of validity ofthe multiplex configuration and the spectrum resources which will befreed including an indication of the period of time during which thespectrum will be available.

FIG. 2 shows a simplified diagram of a dynamic broadcast system 1. Theuser terminal 18 shall be able to display any media content received viaeither of the two delivery paths 2, 3. The control channel 4 allows theNetwork Management Unit (NMU) 24 to monitor the actual media consumptionand to inform user terminals if transmission parameters are modified.

As the user should be able to select the TV service of his choice at anymoment in time, a List of all Services (LoS) available in the network isstored in the device (user terminal 18). Nowadays TV services areassigned to fixed physical and/or logical channels. In DigitalTerrestrial TV (DTT) for example, the transmission parameters for allTransport Streams (TSs) available in the network are carried inside theNetwork Information Table (NIT). In addition the identifiers (IDs) anddescriptors for all services inside a single TS are given by the NIT andthe Service Description Table (SDT) in this TS. As the channelconfigurations are static, a receiver only has to scan through allavailable TSs the very first time it is switched on. During the process,the names of all services and the corresponding transmission parameterscan be saved in a static LoS. In dynamic broadcast, these assignmentswill no longer be static, so that a dynamic LoS is created out of theprovided Signaling Messages (SMs) containing scheduling information andevent-based information for service discovery. The end point of an eventand the start point of a new event will thereby be defined by the pointin time when the changes to the transmission parameters of a single TVservice take place. This means that events are not necessarilyrestricted to whole programs but could consist of various programs or bea subunit of only one program. Each event then could be described as“broadband event” or “broadcast event”. This means further, that thereis the need for unique content IDs which allow to identify a certainpiece of media content or even a content component (e.g. a single audioor video stream, a subtitle of a certain language or a data service)uniquely. By this means, an event then can be assigned to single ormultiple content components so that the TV service during this event canbe created out of these content components. The set of specificationsdescribed in ETSI TS 102 822-2 V1.4.1, “Broadcast and On-line Services:Search, select, and rightful use of content on personal storage systems(“TV-Anytime”); Part 2: Phase 1—System description”, pp. 1-127, November2007 and ETSI TS 102 822-3-1 V1.6.1, “Broadcast and On-line Services:Search, select, and rightful use of content on personal storage systems(“TV-Anytime”); Part 3: Metadata; Sub-part 1: Phase 1—Metadata schemas,”pp. 1-190, July 2010 provide promising approaches to overcome this taskby adding some extensions to the existing framework.

All SMs and updates to previous messages shall then carry a versionnumber or a timestamp referring to a common time base so that the latestinformation can be distinguished from that of older messages. SMs shallbe embedded in the TSs and be repeated periodically or be available fordownload from servers with pre-defined IP connection data as the userterminals need to know which TV services are available in which of thenetworks and where. Otherwise, conflicts might occur for example when auser terminal is switched on for the morning news after it had beenturned off during the night. SMs, the mechanisms for purchasing them aswell as the corresponding update protocols need to be standardized sothat all user terminals inside the network are able to interpret allreceived SMs correctly and to get access to missed updates if there is alack of information. By updating continuously, the linear TV servicescan be built up directly inside the user terminals according to theschedule and the corresponding event information. Thereby the userterminal can be instructed to switch the distribution channel over whichthe single events of a TV service will be delivered. Such switchingoperations are called Network initiated Switching (NiS). It has to bementioned, that the user will not be informed about these processes.Only the names of the available services and a corresponding ElectronicProgram Guide (EPG) will be forwarded to him/her, so that the complexityof the underlying distribution mechanisms will be hidden by theterminal.

NiS differs from a user initiated channel change, as it does not resultin displaying a different media content but in a seamless transition tothe same media content—delivered over a different channel. As anyservice interruption would be annoying, the whole process is performedin a way unnoticeable for the user. Therefore, the respective mediacontent is received on both delivery paths simultaneously for a shortperiod of time. At the end of this phase of parallel delivery, the NiSis completed so that the original reception channel can be shut down bythe Network Management Unit (NMU).

In dynamic broadcast, a user terminal is preferably able to performdifferent types of NiS requiring vertical handovers between thebroadband and the broadcast network or a horizontal handover in thebroadcast network. Broadcast/broadband NiS is performed if the broadcastof a certain service will be stopped and instead, a multicast or unicastdelivery of the same service has been started. Broadband/broadcast NiSis performed if a multicast or unicast of a certain service will bestopped and instead broadcast delivery of the same service has beenstarted. Broadcast/broadcast NiS is performed if the broadcast of acertain service on a certain channel will be stopped while the broadcastdelivery of the same service on a different channel has been started.

The last named NiS operation could also be substituted by sequentialprocessing of a broadcast/broadband NiS and a broadband/broadcast NiS.Further explanation of these switching operations and the description ofan implementation of these processes will be provided below, where livedelivery network switching will be explained.

As already mentioned above, user terminals will have sufficient storagecapacity available to store a large number of programs. This storagespace either could be provided by a built-in hard disk or by a networkattached storage, which is integrated into the home network. Parts ofthis storage capacity might be available for providing functionalitiesof a personal video recorder but a defined part of the storage spaceneeds to be allocated for enabling pre-transmission mechanisms ofdynamic broadcast which allow to distinguish a contents delivery timefrom its presentation time.

First, there are programs which are predicted to be of interest for alarge number of viewers and which in addition are already available fordistribution before their presentation time according to the scheduleand which hence can be seen as Non-RealTime (NRT) content. To name afamous example: “Tatort” would be such a program as it is a movie thatis seen by millions of viewers on Sunday evenings in Germany. In 2010,13 of the 15 most successful movies in German TV had been Tatortepisodes. If these types of programs would be made available aspre-download over broadcast, e.g. during the low-traffic hours the nightbefore, the user terminals could be instructed to record the programbefore its presentation time. This is called network initiated recording(NiR). Then the playback of the content from the storage device wouldreplace online receiving of the corresponding event. Thus, the number ofviewers that watch the program online would be reduced and only theterminals that missed the pre-download would have to receive the liveevent. The whole event thereby could be moved to broadband whereascapacity would be freed in the broadcast network.

Secondly, there is NRT content that might be of lower interest for themajority of users but where in contrast a strong interest in watchingthis program might be predictable for a specific user or a group ofusers. For classifying these types of content and for defining usergroups, data about the individual media usage can be recorded inside theuser terminals and partly be shared with the decision logic. As aresult, content that is more specific could be provided as apre-download via broadband during low-traffic hours which would reducethe load of the broadband network at the presentation time of thecontent. One way of predicting a user's interest in a certain program isto use the outcomes of a recommender system. In principle, therecommender system should make use of implicit feedback (usage history)as well as of explicit feedback (user feedback). Both can be supportedby the data structures described in ETSI, “ETSI TS 102 822-3-1 V1.6.1,”Broadcast and On-line Services: Search, select, and rightful use ofcontent on personal storage systems (“TV-Anytime”); Part 3: Metadata;Sub-part 1: Phase 1—Metadata schemas, pp. 1-190, July 2010.Personalization also offers the possibility to automatically record ausers favorite programs which then can be integrated into a database ofold-NRT content, so that e.g. episodes of favorite series can be addedto a local video on demand platform or be played back from the localstorage in case of repeats. Old-NRT content describes content, whichmight already be available on the terminal's side as it is a repeat of aprogram, which had already been distributed during the last days.

To sum up, the requirements (challenges to user terminals and thedynamic broadcast environment) could be rephrased as follows:

-   -   If the terminal is switched on (maybe for the first time) it        needs to be known which TV services are available in the network        and where.    -   Changes to the transmission parameters for a certain service        mark the start and end points of events, which have to be        signaled to the terminals.    -   Certain pieces of content should be labeled by unique IDs so        that events can be created out of several content components.    -   NiS requires algorithms for a synchronized reception of the same        media content from different media sources.    -   Efficient network management requires reliable recommender        systems on the user terminals side, so that the most appropriate        content may be delivered in advance.    -   System related data will not be forwarded to the users.

In the following, a conceptual architecture for a HBB terminal 18 isdescribed, which aims to meet the requirements introduced above. Thethree main modules of the HBB terminal 18 are depicted in FIG. 3. Themodule device/adapter 181 describes the hardware set-up of the HBBterminal 18 offering accesses to both, a broadcast and a broadbandnetwork, as well as to a built-in storage. In a practical embodimentthese are a DVB-T receiver, a network interface controller and a harddisk. Assisted by the operating system and some device specificApplication Programming Interfaces (APIs) data can be read from thesedevices (media content, signaling messages) and sent to the decisionlogic (acquired data).

The Terminal Management Unit (TMU) 182 is responsible for the managedbuffering of the received Audio/Video (A/V) content and the seamlessswitching between the media sources. To perform these tasks EPG data anddynamically changing channel configurations provided by the decisionlogic 14 as signaling messages have to be interpreted. A detaileddescription on how to realize such processes seamlessly and unnoticeablefor the user will be provided below. The TMU 182 also generates outputdata, which are measurement reports containing information about themedia services watched currently, users preferences and the currentlyavailable QoS.

To display the media content the data are forwarded to the userinterface 183. In case of A/V data these are passed to a media player1831 while service information can be used to build up an adequategraphical user interface in order to enable user requests for examplefor channel switching or accessing a Personal Video Recorder (PVR). Forthat purpose, a list of the available TV channels is created and updatedby the TMU 182 if changes occur. The recommender system is based on userfeedback, program ratings and channel watching history. As it is notimportant how a certain piece of content is delivered, as long as it isavailable at a certain time, the complexity of the architecture of theheterogeneous network should be hidden from the user. Therefore, it hasto be emphasized, that in a dynamic broadcast environment some of thelocal storage capacity is preferably reserved for recordings programmedby the decision logic 14, so that the transmission in advance of NRTevents can be made possible. The playback of such content is thencontrolled by the TMU 182 in relation to the received metadata embeddedin the signaling messages.

As shown in FIG. 3, illustrating the internal flow of data inside theuser terminal, data are first read from a storage or receiving device.After being processed in the Terminal Management Unit 182 selected dataare then routed towards the User Interface 183 (UI). FIG. 4 shows a moredetailed block diagram of an embodiment of a terminal device 18 aaccording to the present disclosure. It can be seen from FIG. 4 that incase of A/V data this would result in displaying them by help of astandard media player application while service specific data are passedto the recommender system engine providing the graphical interface forUser initiated Switching operations (UiS) and recording functionalities.In the following, the functionalities of all modules will be describedin more detail.

With respect to FIG. 3 and FIG. 4, the module named Device/Adapter 181contains all the media sources, which includes broadcast receivingequipment 1811, a broadband interface 1812 as well as a built-in harddisk 1813. As the functionalities of the TMU 182 are preferablyimplemented in software the several devices can be accessed andcontrolled by making use of the operating system and some devicespecific APIs 1814.

The heart of the TMU 182 is a Finite State Machine (FSM) 1821 whichinteracts with the media sources in order to read the content and toobtain SMs, which might arrive via broadcast or broadband. A/V data arepassed through a managed buffer 1822 before they are delivered to themedia player 1831 whereas SMs are directed to a Control Unit (CU) 1823by the Update Interface 1824. Thereby internal data are updated. Such anupdate might affect data that are relevant for the user, like EPG dataor the LoS 1825. In this case, the UI 183 has to be refreshed. It mightalso be the case, that the TV service that is currently watched by theuser is affected by changes. This would mean that the end of the eventthe user is following currently is imminent while the next event isabout to begin. This would then result in a NiS. Therefore the CU 1823has to translate the incoming SMs to well defined instructions, so thata controlled transition of the FSM's status can be realized. In case ofNiS, this would include a synchronization (sync) process, which will beexplained below. It is also possible that the terminal 18 a isinstructed to record a certain piece of content which is going to bepre-transmitted and which afterwards has to be appended to the database.These processes (NiR) have to run in parallel but are also started,interrupted and stopped by changeovers between different states of theFSM 1821. If the recording is finished, eventually the file allocationtable (FAT) has to be updated.

User requests may also enter the CU 1823 and equally lead to statusmodifications once they are interpreted. First there is UiS as a resultof the users wish to watch another program. Secondly, there are userrequests for selecting a program for recording, named User initiatedRecording (UiR). As the user is not informed about whether a certain TVservice is currently transmitted via broadcast or broadband, bothprocesses have to be controlled by the TMU 182. Looking at UiS, the CU1823 has to extract the relevant information from the LoS and toinitiate the corresponding status transition, which might end up in oneof the following states:

-   -   The user is watching a broadcast event.    -   The user is watching a broadband event.    -   The user is watching an event that consists of content, which is        already stored on the hard disk.

In contrast to NiS, UiS will result in a short interruption, but this iswell known and accepted as long as the waiting time is not too long.Obviously, the resulting state of the FSM 1821 has an impact on whatkind of processes can run in parallel. It is suggested that there issufficient data rate available in the broadband network and that inaddition there are two broadcast tuners built into the terminal 18 a sothat at any moment in time one program can be watched while another isbeing recorded. However, even with this assumption made, not everyconflict between user initiated actions and network initiated actionscan be avoided, so that there is the need for a command hierarchy insidethe terminal 18 a which can be stated by: “User initiated actions alwaysgo before network initiated actions.” Only if this is taken intoconsideration the terminals feedback will be reasonable to the user assome processes (NiS and NiR) only run in the background and whichtherefore are unseen by the user. If the command hierarchy is taken intoaccount, only one potential conflict will not be solved. This is whenthere is a running NiR or UiR process recording a broadcast event. Inthis case, a broadcast/broadcast NiS cannot be performed because bothbroadcast tuners will already be in use. That is why the dynamicbroadcast system should always provide the possibility to replace abroadcast/broadcast NiS by a combination of a broadcast/broadband and abroadband/broadcast NiS, so that even a user whose terminal is currentlyin this critical state will not see any interruption of the runningprogram.

Of course, the user can also switch off the terminal. The resultingstate then would be “Standby” or “Off”. “Standby” would still allowupdates, NiRs and UiRs while “Off” would completely disable them.

The Acquired Data 1826 (also called “system signaling information”)describe the output data generated by the user terminal 18 a composed ofsystem specific data, like the current QoS, and user specific data. Thelast named may contain information about the media services watchedcurrently or measurement reports of the recommender system 1832 likechannel switching statistics and the users preferences. These data areof particular importance as the prediction of the user's behavior has agreat impact on the performance of the dynamic broadcast system.

To show how NiS can be realized a demonstrator, which provides one TVservice via three different transmission channels, has been developed.It shall be noted that the layout of the demonstrator(s) explainedhereinafter shall also be understood as embodiment of the layout ofpractical embodiments of a terminal and/or other elements of a dynamicbroadcast system. The user terminal is thereby enabled to switch betweenthese three transmission channels. The sync process which is required ifa NiS needs to be performed is explained below while the demonstrativeenvironment 100 shown in FIG. 5 is introduced in the following, makingreference to FIG. 6 showing NiS operations feasible in the demonstrativeenvironment 100.

It can be seen from FIG. 6 that TV service 1 can be received via threedifferent transmission channels, named BC-1, BC-2 and BB-1. DVB-T isused for the broadcast transmission of BC-1 and BC-2. The broadbandtransmission of BB-1 is realized by User Datagram Protocol/InternetProtocol (UDP/IP) encapsulation of TS packets. This implies that all A/Vdata are packetized into MPEG-2 TS containers. The A/V data are encodedby making use of MPEG-2 source coding. To provide an environment whereone and the same live TV service can be received via these threedifferent transmission channels the redistribution of TV service 1,which is a free-to-air TV service, is implemented. This can be seen fromFIG. 5. The process of redistribution thereby does not include any A/Vrecoding, only TS remultiplexing is done in order to adapt to the datarates available in BC-2 and BB-1. This means that the A/V payload for TVservice 1 is equivalent in all of the three TSs. BC-1 is a free-to-airDVB-T channel which is available in the region of Braunschweig/Hannoverand which is transmitted at 490 MHz using a 16-QAM modulation scheme, an8 k FFT, a guard interval of ¼ and a coding rate of ⅔ for the forwarderror correction (FEC). This results in a data rate of approximately 13Mbit/s, so that four TV services can be carried inside the TS. BC-2,which is transmitted at 634 MHz, includes TV service 1 and 2. The datarate of this TS lies below that of BC-1 at ≈10 Mbit/s due to the usageof another FEC coding rate of ½. The data rate for the broadbandtransmission was set to 6 Mbit/s, which is slightly higher than the datarate, which is required for TV service 1 (≈=4 Mbit/s). By the help ofthis set up an artificial scenario is created where the phase of aparallel delivery of a TV service via multiple transmission channels ispermanent. The mechanisms for NiS, which are an essential requirement touser terminals in dynamic broadcast can thereby be demonstrated, as thedescribed network conditions required at the point in time when there isa transition from one event to the other are present.

As already mentioned the user terminal has been implemented on a PCsystem. A network interface controller and two DVB-T receivers providethe required connectivity. FIG. 6 shows which switching operations arefeasible in the demonstrative environment described above. NiS-1 andNiS-6 are broadcast/broadcast NiS operations whereas NiS-2 as well asNiS-4 is broadcast/broadband NiS and NiS-3, NiS-5 is broadband/broadcastNiS. This means that all NiS operations introduced above and therequired handover mechanisms can be realized in the experimentalenvironment.

Next, it will be described how the sync process during a NiS can beperformed if the correct interpretation of an incoming SM likeintroduced above is assumed. Firstly, a second receiving device has tobe activated in addition to the device, which is currently used for thereception of the running TV program. As an example if referring to FIG.6, NiS-2 would mean, that the currently active device is a broadcastreceiver while it would also imply that the device, which has to beactivated for this NiS, is the broadband interface. During NiS the twoTSs received by these two devices need to be linked together asotherwise visible distortions might occur due to packet-loss. FIG. 7shows a schematic diagram of another embodiment of a terminal 18 b. Itis illustrated how two TSs can be received from the two differentsources in parallel. The example depicted is showing the simultaneousreception of the same TV service via two different transmission paths,which are namely a DVB-T channel and a point-to-point connection overthe IP network. The terminal 18 b comprises a DVB-T receiver 1811 and anassociated buffer 1815, an ethernet adapter 1812 and an associatedbuffer 1816, synchronization information 184, a packet selection &synchronization unit 185 and a media player 1831.

Because of a delay, which might be present between the two correspondingTSs, a certain number of TS packets of both streams need to be bufferedfor a short period of (overlap) time. In an embodiment of a dynamicbroadcast system a maximum value according to this delay is defined sothat NiS can be performed in all of the scenarios introduced above. Inthe demonstrative environment shown in FIG. 5, there is a variable delaybetween the three transmission paths, which deviates from the process ofredistribution. The value of this delay can go up to 4 seconds. Thenumber of TS packets available in the buffer hence is set to 12000,corresponding to approximately 4.5 s of an SD TV service if a data rateof 4 Mbit/s is assumed. From the stored TS packets any informationneeded for the sync process can be extracted. Of high relevance are forexample the order of audio and video packets in both multiplexes as wellas the values of the Program Clock References (PCR) and thecorresponding presentation and decoding time stamps (PTS, DTS).According to the assumptions made above, it has to be emphasized thatthe A/V data carried in both TSs are identical. If so, a merged TS canbe created out of the two input streams and being forwarded to the mediaplayer. Possibly some TS packets are rearranged and/or restamped so thata distortion-free playback can be achieved during decoding by the mediaplayer. The requirements for the synchronization process therefore canbe summarized as follows:

-   -   Every TS packet in the continuous output stream should be        unique.    -   Timebase discontinuities should be indicated.    -   Every PTS and DTS should refer to a valid PCR value.

Next, a summary of the content delivery mechanisms that are used indynamic broadcast are described. In dynamic broadcast, the live deliveryof content can be realized either via a BC network or via a BB network.Each TV service (except virtual channels) can be received live via oneof these networks at any point in time. Thereby, the distributionchannel for each TV service is determined by the network managementsystem. Changes to the transmission parameters for the TV servicesavailable in the dynamic broadcast network are determined by the networkmanagement system and signaled to the receivers. Such changes lead toNetwork initiated Switching (NiS)—a process performed by the receivers,which results in a seamless transition to another distribution channel.In dynamic broadcast, a TV service can be moved from a BC channel to aBB channel (NiS-2-BB) or vice versa (NiS-2-BC). In order to allow for aflexible configuration of the BC multiplexes, it is also possible tomove TV services between different BC channels. Such switching of the BCchannel can be performed directly in case that there is an additional BCtuner available in the receiver. In order to accommodate receivers thathave only a single BC tuner, the TV service will be transmittedadditionally via BB for a short period, so that the (direct) NiS-2-BCcan be substituted by a sequential processing of NiS-2-BB and NiS-2-BC.As the distribution channel can be changed at short notice, thefollowing requirements will have to be met:

-   -   If the TV service currently watched is received via BB, a BC        tuner shall be in stand-by, so that a NiS-2-BC can be performed        at any time.    -   If the TV service currently watched is received via BC, enough        capacity of the BB connection shall be reserved to allow for the        reception of the same TV service, so that a NiS-2-BB can be        performed at any time.

In addition to the live delivery of TV content via the heterogeneousnetwork, there are non-real-time delivery mechanisms in dynamicbroadcast, which can make use of either of the networks. Firstly, thereis the pre-transmission via BC, which aims to distribute a certain pieceof content to all terminals able to receive the BC signal. Secondly,there is the pre-download of content via BB, which is performed byterminals whose users are predicted to have a strong interest inwatching a specific piece of content. Both delivery strategies aim toreplace the live reception of content at the presentation time accordingto the broadcast schedule by enabling the receivers to Play backpre-stored Content (PbC).

In order to avoid the multiple transmission of content, which isrepeated by the broadcaster, receivers can also be instructed to recordthe live stream during its first play out. As the distribution channelmight change during this process, NiS has to be performed inside thereceiver to guarantee for uninterrupted recording.

From the perspective of the receiver, the delivery techniques describedabove can be termed as Network initiated Recording (NiR). Theseprocesses are planned and scheduled by the network management. However,the number of BC tuners and the BB capacity available on the receiver'sside will differ between households. Thus, a number D′ of programs hasto be selected for recording as a subset of all indicated live andpre-transmitted programs D. Supposed, that the users (or group of users)interest in the individual programs can be predicted, D′ can be foundand the recordings can be scheduled by the method proposed in J. Korst,V. Pronk, M. Barbieri, W. Verhaegh, and W. Michiels, “Scheduling TVrecordings for a recommender-based DVR,” 2010 IEEE 14th InternationalSymposium on Consumer Electronics (ISCE), pp. 1-6, July 2010, assumingthat a pair of one BC tuner and one BB channel needs to be reserved forinterruption-free recording.

FIG. 8 provides a high-level block diagram of the internal hardware andsoftware components of another embodiment of a demonstrator 200, butalso explains which elements are used in practical embodiments of adynamic broadcast system. In the system demonstrator, the BCtransmission of media content is carried out using DVB-T, whereas a UserDatagram Protocol (UDP) is used to deliver media content via the BBlink. Signaling information 216 can be embedded inside the TransportStreams (TS) or be sent as separate messages via the bidirectional BBconnection.

The network management unit 202 is equipped with play out equipment,namely a DVB-T modulator card 204 (representing an embodiment of thebroadcast transmitter) for generating the BC signal and an ethernetcontroller 206 (representing an embodiment of the broadbandtransmitter/server from which the content can be actively provided(“transmitted”) to a terminal and/or passively “provided”, e.g. fordownload by a terminal). Both devices are controlled by a real-time(Re-) multiplexing unit 208 (e.g. programmed by software).

As can be seen from FIG. 8, the network management application 202 canbe controlled by a graphical user interface (GUI) 210. Thereby, thedynamic broadcast TV service can be started/stopped and the mediacontent to be transmitted can be selected out of a content pool 212,which provides a set of locally stored DVB TSs containing standarddefinition (SD) TV programs. The selected content is then packed asdescribed above in a content packaging unit 213 before it is provided tothe multiplexing unit 208. Further, NiS and NiR can be triggered. Thedecision logic 214 allows simulating the optimization processesperformed in a dynamic broadcast network. Therefore, input datadescribing the behavior of large audiences are emulated and combinedwith the monitoring reports received from the implemented receiver atthe monitoring information receiver 217. The transmission parameters 218are adapted as an outcome of the optimization algorithms and signalingmessages are sent to the receiver accordingly.

FIG. 9 shows another embodiment of the receiver (user terminal) 18 caccording to the present disclosure, which is equipped with two DVB-Ttuners 1811 a, 1811 b and an Ethernet controller 1812. Thereby, the RFsignal as well as the UDP stream(s) provided by the network managementunit can be received. Signaling messages can be obtained and monitoringreports can be sent via a bidirectional IP connection.

The central software module of the receiver is the terminal logic 186,which can be described as a finite state machine (FSM) interacting withthe DVB-T tuners 1811 a, 1811 b, the Ethernet controller 1812 and thelocal Hard Disk Drive (HDD) 1813. These devices provide the input datato the terminal logic 186. The main functionality of the terminal logic186 is to automatically select the proper source for receiving the mediacontent to be displayed and to be recorded. Therefore, incomingsignaling messages are analyzed. The output of the terminal logic 186are media content data, which are either written to the HDD 1813 wherethey are stored for later playback or routed towards a standard mediaplayer 187, which does the audio and video decoding of the contentcurrently being watched. For displaying the media content, a TV set 19is connected via the HDMI interface 188 of the receiver 18 c.

In the following it is explained how the signaling messages obtainedfrom the network management have effect on the FSM. Thereafter adetailed description of how media content data are processed by theterminal logic depending on the state of the FSM is provided.

Based on the conceptual architecture of a receiver described above withreference to FIG. 4, a software module is provided that manages theinteraction between the media sources available to the receiver, whichin this case are an Ethernet connection, two DVB-T tuners and a HDD witha storage capacity of 1 TB.

FIG. 10 shows a transition diagram 300 of an active receiverillustrating how the interaction of these devices is realized byillustrating the states of the active receiver and the possibletransitions between these states, which could either be initiated by thenetwork management (NiS and NiR) or be triggered by the terminal itself(PbC). User initiated actions are not considered in this diagram.Instead, the focus is on the processes running in the background while auser is watching a certain TV service, composed of live content(received via BC or BB) and pre-stored content played back from the HDD.Further, the demonstrator allows content to be recorded simultaneouslyand independently of the delivery network. For this purpose, it isassumed that there is sufficient capacity in the BB network forreceiving two TV programs in parallel.

If so, the requirements stated above can be fulfilled, so that NiS canbe performed at any time when signaled by the network management. Thus,the internal state transitions of the terminal logic can be explained asfollows: The state of the FSM will be BC-Live or BB-Live if the contentcurrently watched is not available on the local HDD and no recording isin progress. If a NiS is triggered by an incoming signaling message, atransition from BC-Live to BB-Live will be performed in case the live TVservice is moved to BB (NiS-2-BB). On the other hand, the new state ofthe FSM would be BC-Live if the TV service is no longer delivered viathe BB link but instead moved to a BC multiplex as result of a NiS-2-BCtransition. In a dynamic broadcast system, where more than one singleDVB transponder is used, TV services might also be moved betweendifferent BC multiplexes. Therefore, the receiver is capable ofperforming NiS-2-BC also if the start state is BC-Live.

To integrate the HDD into the operation of the receiver the uniqueidentifiers for each media content present in the broadcasting scheduleare derived from the received signaling messages. Every 15 seconds it ischecked, whether the media content currently watched is already storedon the HDD. If so, the playback of this content is initializedautomatically (PbC-Start). During the replay (HDD), the ongoing changesin the network are recorded but NiS operations are ignored. If the endof the stored media file is eminent, the technical parameters of thecurrent distribution channel are loaded so that the transition back tothe live stream (BC-Live or BB-Live) can be performed (PbC-Stop). Whenthe media content following subsequently is also stored on the HDD, thenPbC-Start is performed instead of PbC-Stop and the state remains HDD.

If a NiR process is indicated by the network management, a parallelrecording thread is created (NiR-Start) by the terminal logic and thestate of the FSM is changed depending on the distribution channels ofthe TV service currently watched and the media content to be recorded.To give an example it shall be assumed that a NiR-Start is beingprocessed while the FSM has been in the state BC-Live. The resultingstate then could be the topmost shown in FIG. 10, BC-Live & BC-Rec,where one BC tuner is used for receiving a live TV service while theother BC tuner is used for recording. At one time the FSM can only be inone state or perform one transition between two defined states.Therefore transitions between the substrates BC-Live, BB-Live, HDD,BC-Rec and BB-Rec can only be processed subsequently. In the aboveexample this means, that if there are two NiS-2-BB operations affectingthe TV service watched live as well as the recorded program, these haveto be processed in sequence based on the arrival time of thecorresponding signaling messages. If for any reason these times cannotbe distinguished, the NiS-2-BB of the currently watched TV service isqueued first. So the transition from BC-Live to BB-Live would then bethe first step followed by the changeover from BC-Rec to BB-Recresulting in the end state BB-Live & BB-Rec.

In the following it is discussed how the buffering of media content datais realized inside the terminal logic in order to allow for itsinterruption free presentation and recording in presence of NiSoperations. As described above a NiS requires the simultaneous receptionof identical media content via two different distribution channels inorder to allow for the compensation of the delay, which might be presentbetween both of them. In the present implementation MPEG-2 TSs are usedto deliver the media content. The terminal logic therefore has beendesigned for the processing of multiple input streams.

FIG. 11 shows another embodiment of a terminal 18 d including a detailedoverview of the terminal logic's software components. As can be seen,the input data are provided by several interfaces. These are: theSignaling & Monitoring Socket 191 for receiving signaling messages andsending monitoring reports, the Media Socket(s) 192 for receiving theUDP stream(s), the DVB API (Application Interface) 193, which allows tocontrol both DVB-T tuners and the HDD I/O 194, whereby media content canbe read and written from/to the local hard disk.

Signaling information arriving via the IP network is directly forwardedto the Control Unit 196, whereas the signaling information embedded inthe TSs first need to be extracted by a PID Filter 197. Both types ofsignaling messages are then interpreted by the Control Unit andtranslated to pre-defined events. Thereby, state transitions of the FSMare triggered.

Next, the internal buffer management in the absence of NiS is described.In case that the FSM is in one of the defined states, the media contentdata are simply routed towards the FIFO (First In—First Out) contentbuffers 195 a, 195 b so that the module TS Merging and Alignment 198,provided for merging and alignment of the media content data to betransmitted, is bypassed. The Source Selection module 199 thereby isresponsible for routing the arriving TS packets to their desireddestination so that the TS to be recorded is written to the HDD and theTS to be decoded is forwarded to the Stream Buffer 190, which providesthe output interface of the terminal logic to the A/V decoder (see FIG.9). It is necessary to store a number of TS packets for a short periodof time in order to be able to compensate the delay between twodistribution channels in case of NiS. For recording, a FIFO buffer offixed size (12000 TS packets) is used. Using a fixed buffer size ispossible as the media content does not need to be decoded in real-timebut rather is just written to a file. In contrast, the size of thepreceding FIFO buffer, which is used for caching the TS packets to bedecoded, is time variant. This is necessary, as the data rate of the TSis not constant. Consequently, a constant delay through the buffer canonly be achieved if the buffer fullness varies with the data rate.Therefore, the delay through the buffer is set to a fixed delay timeT_(D) and the arrival time of each TS packet at the FIFO is measured andstored in a variable t_(n). The TS packets then are retained for thedelay time T_(D), before they are released.

FIG. 12 shows an exemplary result by illustrating the time variantbuffer size in units of TS packets, which has been recorded during aplayback time of 60 s. In this example, the delay time T_(D) was set to3.5 s. As can be seen from FIG. 12, the maximum number of stored TSpackets was 10800 during the experiment, while the smallest buffer sizewas approximately 6300 TS packets. In other words, the data ratefluctuated between 2.7 Mbit/s and 4.6 Mbit/s.

Next, the internal buffer management in the presence of NiS isdescribed. In principle, the algorithms implemented for performing NiSare the same for the continuous playback as for the continuous recordingof media content. However, due to the management of the time variantbuffer it is the more challenging case to perform NiS for a TV programwatched live. Therefore, the transition between the FSM states BC-Liveand BB-Live will be used to explain the terminal internal processing.

As the transition NiS-2-BB is triggered, the first step performed by theTerminal Logic is to switch-on the Media Socket interface. Then the TSMerging and Alignment module is activated. To start the simultaneousreception of both TSs, the Source Selection settings are changedsubsequently and a timer is started for a data acquisition phase, whichlasts for a duration of T_(DAP). Consequently, the TS packets from bothsources are routed towards the TS Merging and Alignment module. Duringthe data acquisition phase the TS packets arriving via the newdistribution channel are stored in a linear buffer B_(new) inside theMerging and Alignment module, while the TS packets arriving via thecurrent distribution channel are forwarded to the FIFO buffer. The dataacquisition phase ends if the timer reaches T_(DAP). Then thesimultaneous reception is terminated and the sync process is started.For the synchronization the data stored in B_(new) and in the FIFObuffer need to be combined to one single stream. As both TSs carry thesame media content, the payload of the TS packets can be compared tofind packets of identical payload in both streams. The sync point, whereboth streams will be aligned, will then be indicated at a random accesspoint of the video elementary stream (a video packet where therandom_access_indicator is set).

All packets of the FIFO buffer, which arrived after the sync point, willbe deleted (including the sync packet itself). Instead, thecorresponding packets stored in B_(new), will be inserted. The programclock reference (PCR) value of the discarded sync packet is stored forlater use in a variable P_(cur). The PCR value of the inserted syncpacket is P_(new). Then, depending on the constitution of the receivedTSs, the deletion and/or the reordering of audio packets might benecessary. Further, the presentation time stamps (PTS) and decoding timestamps (DTS) of reordered packets might have to be modified, so thatthey refer to a valid PCR. At the sync point, the discontinuity flag isset, so that the discontinuity of the video elementary stream'scontinuity counter and PCR is indicated to the A/V decoder. Finally, thedata stored inside the FIFO buffer will then represent a merged TS. Thisprocedure turned out to ensure seamless decoding of the output stream inthe demonstrative environment described above. The sync process willaffect the number of stored TS packets inside the FIFO buffer. In caseof a positive delay between the current and the new distribution channelthe buffer size will be reduced, whereas a negative delay will increasethe number of stored TS packets. Therefore, it is mandatory to reset thedelay time T_(D). The new delay time T_(Dnew) can be estimated from theTS packets stored in the FIFO buffer. To do so, the TS packetscontaining a PCR field need to be identified. Preferably, the programclock reference base is used, which, if present in a TS packet, isstored in a 33-bit field. The program clock reference base is in unitsof f_(PCR)=90 kHz, so that in principle, the time distance t_(dis)between two TS packets k and l, which both provide a PCR field, can beapproximated by the difference of the PCR values P_(l) and P_(k).Equation (1) is used to calculate the PCR difference P_(diff) of two PCRvalues under the assumption that TS packet k arrived earlier than TSpacket l:

$\begin{matrix}{{P_{diff}\left( {P_{k},P_{l}} \right)} = \left\{ \begin{matrix}{{P_{l} - P_{k}}\mspace{59mu}} & {{{for}\mspace{14mu} P_{l}} \geq P_{k}} \\{2^{33} - P_{k} + P_{l}} & {{{for}\mspace{14mu} P_{l}} < P_{k}}\end{matrix} \right.} & (1)\end{matrix}$

The time distance t_(dis) between the two TS packets k and/then can beapproximated by

$\begin{matrix}{t_{dis} = {{P_{diff}\left( {P_{k},P_{l}} \right)} \cdot {\frac{1}{f_{PCR}}.}}} & (2)\end{matrix}$

As result of the synchronization process, a discontinuity of the PCRvalues has to be expected at the sync packet. As this has to beconsidered during the approximation of the new delay time T_(Dnew), wemake the following assumptions: The first TS packet stored in the FIFObuffer that provides a PCR field is named a. The last packet stored inthe FIFO buffer with a PCR field is named z. Now, T_(Dnew) can bederived from the following equation:

$\begin{matrix}{T_{Dnew} = {\left( {{P_{diff}\left( {P_{a},P_{cur}} \right)} + {P_{diff}\left( {P_{new},P_{z}} \right)}} \right) \cdot {\frac{1}{f_{PCR}}.}}} & (3)\end{matrix}$

The arrival times of the TS packets, stored in the FIFO buffer also haveto be reconstructed after the sync process. An iterative algorithm hasbeen implemented to perform this task. Thereby, a pair of two TS packetsproviding a PCR value is created in each iteration step and the numberof TS packets N, which are in between, is counted. Then the timedistance t_(dis) between both of them is calculated. Under theassumption, that the data rate between these two adjacent PCR values isconstant, the time distances to the intermediate TS packets of thefragment, can be approximated. For that, the constant time segmentΔt_(dis) is computed by (4):

$\begin{matrix}{{\Delta \; t_{dis}} = \frac{t_{dis}}{N + 1}} & (4)\end{matrix}$

Where no pairs can be created as the margins of the buffer are reached,the time segment Δt_(dis) of the previous fragment is used. To start theiteration process, it is assumed that the TS packet stored last, arrivedat the time when the sync processed finished. Thus, the arrival time foreach precedent packet can be recalculated. When the sync point isreached, the calculated arrival time for the sync packet is reused forthe next iteration step but instead of using the P_(new) for furtherprocessing, the PCR of the discarded sync packet P_(cur) is utilized forthe next fragment in order to compensate the discontinuity of the PCR.

After recalculating an arrival time for each of the stored TS packets,the state transition process can be finalized. Therefore, the end of theprocessing is signaled by the TS Merging and Alignment module to theControl Unit, so that the state of the FSM can be updated to BB-Live.Subsequently, only the TS packets arriving via the Media Socket areforwarded by the Source Selection module to the FIFO buffer. The BCtuner, which is no longer needed, is switched-off by the Terminal Logic.Due to the varying processing time, needed for the synchronization, andinaccuracies in the measurement and recalculation of the arrival timesof the buffered TS packets, slight time discontinuities might be presentin the output stream. However, the Stream Buffer downstream the FIFObuffer allows to smooth out these time discontinuities.

FIG. 13 shows the course of the buffer fullness in units of TS packetsin presence of NiS. The measurement took place in an experiment, whereduring a playback time of 60 s, three NiS operations were indicated. Atthe beginning, the delay time T_(D) was set to 3.5 s and the maximum theduration of the data acquisition phase T_(DAP) was set to 2.5 s. Theamount of the Stream Buffer was initially set to 1.5 s, so that a totaldelay through the buffers, from the DVB API to the output of the StreamBuffer, of 5 s resulted.

The start state of the FSM had been BC-Live. Then a state transitionfrom BC-Live to BB-Live was performed followed by a NiS-2-BC transition.The end state, BB-Live, was then achieved by another NiS-2-BBtransition. One can clearly identify the points in time, when the NiSoperations had been completed and the transition processes werefinalized by the jumps of the curve in FIG. 13. These can be found at 18s, 34 s and 48 s respectively. Obviously, the buffer fullness increasedafter the first NiS, what indicates, that the broadcasted TS is delayedwith respect to the UDP stream. The same can be observed from thebehavior of the curve at the two following NiS operations.

FIG. 13 clearly shows, that the delay time T_(D) must always be largerthan the maximum channel delay T_(Cmax), as otherwise a buffer under runmay occur during a NiS. On the other hand the duration of the dataacquisition phase must be long enough to compensate for the maximumchannel delay (T_(DAP)>T_(Cmax)). Further, the maximum time distancebetween two random access points Δt_(RAmax) must be considered todetermine T_(DAP), as only TS packets that provide a random access flagcan be used as sync point. It can be assumed that therandom_access_indicator is set whenever a random access point occurs inthe video stream. A random access point usually occurs during less than0.5 s, so that Δt_(RAmax) can be set to 0.5 s. As the sync process mightalso require the reordering of some audio packets located before andright after the sync point, an additional reserve t_(r) should also beconsidered for example by half of the time distance Δt_(RAmax). IfΔt_(RAmax) is chosen to 0.25 s and the data rate of the encoded audio isassumed to be 192 kbit/s, then a minimum number of 32 audio packets willbe available after the sync point. During an experiment, where 50 NiSoperations were processed subsequently the delay was measured betweenthe broadcasted TS and the UDP stream by comparing the arrival times ofthe sync packets. In these experiment the maximum channel delay F_(Cmax)turned out to be 0.832 s. Following the equation

T _(DAPmin) =T′ _(Cmax) +Δt _(RAmax) +t _(R)  (5)

the minimal duration for the data acquisition phase T_(DAPmin) in theabove described demonstrative environment can be approximated to be1.582 s. As T_(D) must always be larger than T_(DAP) in order to avoid abuffer under run, it turned out to be a good choice to set T_(D) to avalue 1s larger than T_(DAP). However, the minimum value of T_(D),T_(Dmin), can be derived from T_(DAPmin) as it needs to be ensured, thatthere are always audio packets located before the sync packet inside theFIFO buffer, even in case that the maximum channel delay T′_(Cmax) ispresent. The minimum delay through the FIFO buffer T_(Dmin) thereforeequals 1.832 s.

In an embodiment of the terminal said system signaling informationcomprises information on content provided for offline delivery,information on the time of broadcast of content via said broadcastnetwork, information on the time of transmission of content via saidbroadband network, a program schedule, a delivery network indicatorindicating for which period of time and/or how often stored content isto be used and/or information about parameters of multiplexing and/orcoding of data representing content.

In an embodiment of the broadcast system the broadband server and/orsaid broadcast transmitter is configured to transmit system signalinginformation comprising information on content provided for offlinedelivery, information on the time of broadcast of content via saidbroadcast network, information on the allocation of content to multiplexcontent data streams, information on the time of transmission of contentvia said broadband network, a program schedule, a delivery networkindicator indicating for which period of time and/or how often storedcontent is to be used and/or information about parameters ofmultiplexing and/or coding of data representing content.

In another embodiment of the terminal said signaling informationprocessor is configured to generate a dynamic list of services and/orcontent available in said storage device and available for reception viasaid broadcast network and/or said broadband network from said systemsignaling information.

In another embodiment of the terminal said signaling informationprocessor is configured to process content identifiers assigned tocontent or content components for generating said dynamic list.

In another embodiment of the terminal said broadcast receiver and/orsaid broadband receiver are configured to retrieve system signalinginformation in a pull mode and/or to receive signaling information in apush mode.

In another embodiment of the terminal it further comprises a userinterface that receives a user's requests.

In another embodiment of the terminal said storage device is configuredto buffer the content received during a predetermined overlap time fromboth receivers and that said management unit is configured tosynchronize the two received content data streams of said content and toswitch from one content data stream to the other content data streamafter said synchronization.

In another embodiment of the terminal a delay through said storagedevice is set to a predetermined delay time and said storage device isconfigured to measure and store the arrival time of received contentdata packets.

In another embodiment of the terminal said management unit comprises afinite state machine.

In another embodiment of the terminal said management unit is configuredto process requests for network initiated switching, network initiatedrecording, user initiated switching and/or user initiated recording.

In another embodiment of the terminal it further comprises apresentation unit coupled to said output unit that presents contentoutput by said output unit to a user.

FIG. 14 shows another embodiment of a proposed dynamic broadcast system1′. In this embodiment the decision logic 14′ communicates withsecondary spectrum users. The intermediate stage is the dynamic whitespace database unit 26, which can be operated by the broadcast networkoperator himself or any other assigned database operator.

The dynamic white space database unit 26 is not only a table of spectrumusage information. It rather can be regarded as a spectrum managementdevice 27 together with a spectrum server 28 that handles spectrumrequests and assigns frequency bands to specific users. The spectrumserver 28, which may be a separate element as shown in FIG. 14 but mayalso be part of the decision logic 14′ (or its tasks may even beperformed by the decision logic 14′) takes control of the database andprovides a logic to optimize the overall spectrum usage. Furthermore, itenables the communication between the spectrum users and the database.

Primarily, there are two types of spectrum users: the dynamic broadcastnetwork 1″ as the primary user and different kinds of secondary users 18(also called white space devices herein). A secondary user could forinstance consist of a base station (master) and several mobile stations(slaves). It is possible that in this master/slave configuration onlythe master communicates with the spectrum server 28. The dynamicbroadcast network has the highest priority. If the decision logic 14′decides to consume a certain part of the spectrum, the spectrum server28 manages the frequency resources accordingly, trying if possible tosatisfy the remaining spectrum users in terms of TVWS capacity. Thepriority of different secondary users can be graded in the same way, iffor instance a white space WiFi network is privileged over a white spacesensor network.

For other white space databases TVWS are calculated once and then remainstatic. In case of the dynamic white space database unit 26, incontrast, one has to deal with dynamics of the primary user. Therefore,not only white space devices (WSDs) but the broadcast network operatorhas to register in the database as well. Frequency resources required bythe broadcast network operator are automatically updated by means of thedecision logic 14′. On the other hand, the spectrum server 28 can returninformation on spectrum demand of secondary users as an input to theoptimization algorithms of the dynamic broadcast network. The decisionlogic 14′ can therefore take the spectrum demand of secondary users intoconsideration when configuring the packaging unit 12 for packaging ofmedia content as well as other units in the dynamic broadcast systemshown in FIGS. 1 and 14.

The decision logic 14′ configures the whole dynamic broadcast network inorder to achieve an optimal operating state at each point in time.Therefore, the delivery network and the delivery time of media contentare planned in accordance with content popularity, watching behavior anduser interests. In addition, the time-variant demand of secondary usersfor white space spectrum is taken into account. It is unnecessary tomake white space spectrum available in times when secondary users cannotmake use of it (e.g. at night). For that reason, the spectrum server 28summarizes TVWS requests from secondary users and provides an additionalinput variable to the decision logic 14′ algorithms. The optimaloperating state of the dynamic broadcast network is then constituted bya trade-off between media delivery cost, energy consumption and spectrumefficiency.

Even though the dynamic broadcast network is the primary user, thedynamic white space database unit 26 treats it like any other spectrumuser who wants to make use of available TVWS. In other words, from theperspective of the dynamic white space database unit 26 the whole of theTV spectrum is considered TVWS. To maintain the primary status of thedynamic broadcast network, which is allowed to make use of any frequencyband at any time, the prioritization of spectrum users is exploited.Having the highest priority, dynamic broadcast can displace secondaryusers from a certain TVWS, which is taken care of by the spectrum server28.

Since the dynamic broadcast network is registered in the database,potential interferences to broadcast receivers caused by secondary userscan easily be handled. When user terminals inform the decision logic 14′about bad receiving conditions, the transmit power of the terrestrialbroadcast transmitters can be increased. This is communicated to thespectrum server 28, which recalculates the TVWS availability and, wherenecessary, revokes assigned TVWS channels from secondary users.

Next, the general structure and tasks of the dynamic white spacedatabase unit 26 and the spectrum server 28 are explained

As for other white space databases, the dynamic white space databaseunit 26 is responsible for processing spectrum requests, performingcalculations and returning lists of usable TVWS. The results of theselists typically comprise usable frequency bands and correspondingmaximum permitted transmit powers. In practice, these tasks are carriedout by the spectrum server 28, which manages the database contents.

The dynamic white space database unit 26 may be implemented as arelational database. Spectrum users, including dynamic broadcast as theprimary user, have to register in the database, obtaining a unique userID as the result (‘Database ID’). All registered spectrum users havecustomized attributes such as their geographical position, transmitpowers, bandwidth requirements etc, stored in the database. An importantattribute is the spectrum user priority, which in case of the dynamicbroadcast network has the highest possible value. An additionalattribute is a list of assigned dynamic TVWS channels, consisting of thefrequency bands and the start and end time of TVWS validity. AssignedTVWS channels are uniquely defined by the ‘TVWS ID’. The contents of thedynamic white space database unit 26 must be automatically updated whenchanges of spectrum usage occur (or if changes are scheduled,respectively).

Adjustments of dynamic broadcast network parameters are scheduled by thedecision logic 14′ in advance. Hence, the dynamic white space databaseunit 26 offers the possibility for WSDs to schedule available TVWS alsoin advance. A WSD may for instance request a TVWS channel with asufficiently high permitted transmit power for three hours between 6 and9 p.m. the next day. Due to these dynamics, the contents of the dynamicwhite space database unit 26 differ from the contents of other whitespace databases in one respect: Each entry in the database is matched toa time table which determines the period of validity of this entry. Soin addition to conventional contents of a white space database unit 26like transmitter locations and transmission powers, a time table isprovided that specifies start time and end time and hence the dynamicsof each TVWS channel.

The calculations performed by the spectrum server 28 have to take thedimension of time into account. A spectrum user might have minimumrequirements of the TVWS validity time or is interested in a TVWSchannel only for a certain time of the day. In summary, the spectrumserver 28 determines available TVWS by the characteristics frequency,bandwidth, permitted transmit power, geographical area and time. Furtherclassification may include the spectral power density or adjacentchannel leakage of a WSD, respectively.

The spectrum server 28 provides all necessary communication protocolsrequired for a smooth operation. Conflicts are handled according to thepriority and type of the spectrum users involved. Further, the spectrumserver 28 offers the possibility for secondary users to register in theso-called dynamic white space database queue, in order to be informed assoon as an appropriate TVWS is available.

The connection between spectrum users (clients) and the spectrum server28 has to be established and maintained. Without this connection a WSDis not allowed to be put into operation, since TVWS availability is notfully predictable and changes over time. Two communication modes exist.Firstly, the ‘Poll Mode’ allows spectrum users to consult the dynamicwhite space database unit 26 on their own. Secondly, the spectrum server28 makes use of the ‘Push Mode’, which allows informing spectrum usersabout changes. The ‘Push Mode’ is necessary for revoking assigned TVWSchannels, if a spectrum user with higher priority wants to use aparticular TVWS channel.

Since for one WSD there might be a TVWS channel available, while therequirements of another WSD might exceed the capacity of this channel,all spectrum users have to provide their required transmissioncharacteristics when requesting spectrum. Likewise, they have to providea device type classification, so there are no miscalculations and thespectrum server 28 can find appropriate TVWS spectrum. Specific spectrumuser properties like spectral masks, modulation schemes and antennagains can be identified by means of the device type classification.

When requesting a TVWS channel, information required by the dynamicwhite space database unit 26 is delivered in an object called TVWSfilter. The following data are preferably in the TVWS filter:

Device type,

Database ID (or a request for a new ID),

Signature for authentication,

IP address for push-messages (host, port),

Geographical position in the form of latitude, longitude and height,

-   -   Accuracy of the geographical position    -   Maximum transmit power    -   Lowest frequency usable (‘Discover’)/lower TVWS band edge        (‘Request’)    -   Highest frequency usable (‘Discover’)/higher TVWS band edge        (‘Request’)    -   Minimum required bandwidth of TVWS (‘Discover’)/TVWS bandwidth        (‘Request’)    -   Earliest time of TVWS (‘Discover’)/TVWS start time (‘Request’)    -   Latest time of TVWS (‘Discover’)/TVWS end time (‘Request’)    -   Minimum required duration of TVWS (‘Discover’)/TVWS duration        (‘Request’)

Depending on the type of message (‘Discover’/‘Request’, see below) somedata have a different meaning. If a WSD sends a ‘Discover’ message, thefrequency range for instance usually spans the whole usable frequencyrange of the device. If on the other hand a ‘Request’ message is sent,the frequency range focuses on a specific desired TVWS channel.

Optional data in the ‘TVWS Filter’ are a ‘Pushexpire’ time stamp and thespecification of multiple geographical positions. If a WSD wants to beput in the dynamic white space database queue, it has to provide avalidity period of the request in form of the ‘Pushexpire’ time stamp.Multiple positions can be handed over to increase the operating range ofmobile devices or to specify the positions of the slaves in amaster/slave configuration.

A smooth operation is guaranteed by a well defined communicationprotocol between the spectrum users and the spectrum server 28, which isspecified below. Spectrum users (clients from the perspective of thespectrum server 28) can send the following messages to the spectrumserver 28:

‘Discover’: If a spectrum user wants to obtain a list of possible TVWS,he can send a ‘Discover’ message to the spectrum server 28. The spectrumserver 28 takes the requirements of the spectrum user into account,calculates possible TVWS channels by means of the dynamic white spacedatabase unit 26 and returns a list of these channels in a ‘TVWS Info’message. The spectrum user can then choose between the offers by sendinga ‘Request’ message. A ‘Discover’ message must be coupled with a ‘TVWSFilter’ object.

‘Request’: In order to obtain a specific TVWS channel, a spectrum usermust send a ‘Request’ message to the spectrum server 28. Usually, a WSDwill send a ‘Discover’ message before and choose from a list ofavailable TVWS channels returned by the spectrum server 28. However,this step is optional and a WSD might as well request a TVWS withoutbeing sure about the actual TVWS availability. This can be useful tosave communication overhead, if a WSD assumes a certain TVWS channel tobe available (e.g. due to spectrum sensing results). A ‘Request’ messagemust be coupled with a ‘TVWS Filter’ object.

‘Release’: If a spectrum user does not need an assigned TVWS channelanymore, he can release this channel by sending a ‘Release’ message tothe spectrum server 28. The ‘Release’ message helps the spectrum server28 to increase TVWS efficiency, since unused frequency bands canimmediately be offered to other spectrum users. If the connectionbetween a spectrum user and the spectrum server 28 is lost for aspecific period of time, assigned TVWS channels are revokedautomatically, without the need for this message. A WSD which has noconnection to the spectrum server 28 for this amount of time must ceaseany transmissions in order to avoid potential interferences.

‘Queue Confirm’: If a ‘Discover’ message does not bring a satisfyingresult, WSDs get the possibility to be put on the dynamic white spacedatabase queue by sending a ‘Queue Confirm’ message. As soon as anappropriate TVWS is available, they will be informed by the spectrumserver 28 by means of a ‘TVWS Push’ message. To inform the spectrumserver 28 how long the WSD is willing to wait in the queue, the‘Pushexpire’ time stamp has to be attached to the ‘Queue Confirm’message.

The spectrum server 28 can send the following messages to its clients:

‘TVWS Info’: This is the answer to a ‘Discover’ message from a spectrumuser. The ‘TVWS Info’ message contains a list of usable TVWS channelsmatching the requirements of the spectrum user. If no such TVWS channelis available, an empty list with an incorporated ‘Queue Propose’ message(see below) is returned.

‘Grant’: The ‘Grant’ message confirms a TVWS request. WSDs are onlyallowed to use a TVWS channel, if they have received the ‘Grant’ messageand remain connected to the spectrum server 28. In order to avoidinterferences with other previously active spectrum users in the sameband, the ‘Grant’ message may contain a recommended waiting time, duringwhich the other spectrum users can safely terminate their wirelessconnection. The ‘Grant’ message includes the unique ‘TVWS ID’ for therequested TVWS channel.

‘Reject’: This is the opposite of the ‘Grant’ message. A WSD whichreceives a ‘Reject’ message as the answer to a ‘Request’ message, is notallowed to use a requested channel as previously specified in the ‘TVWSFilter’.

‘Revoke’: The spectrum server 28 can revoke an assigned TVWS channel atany time by sending a ‘Revoke’ message. Therein, the corresponding ‘TVWSID’ is given. The affected WSDs get the possibility to be put on thedynamic white space database queue with the same or a similar ‘TVWSFilter’ as for the previously assigned TVWS channel (‘Queue Propose’,see below). Alternatively, the WSD can start a new ‘Discover’ and‘Request’ process. The ‘Revoke’ message is important to handle thedynamics the time-variant behaviour of dynamic broadcast, since changesof spectrum usage may occur at any time. Usually, a revoke will be setinto the future, giving a WSD enough time for adjustments. If however aTVWS channel has to be cleared immediately, the ‘Revoke’ message willcontain a short fadeout time, during which the WSD can safely terminateits wireless connection. The same applies to the ‘Trim’ messagedescribed hereafter. The primary user can never be affected by a‘Revoke’ message.

‘Trim’: This typical push message is sent to a client, if his assignedTVWS channel is scheduled to be occupied by a higher priority spectrumuser only for a short period of time. Instead of revoking the TVWSchannel completely the allowed usage time is trimmed by an interval. Theclient can accept the ‘Trim’ or decide to release the TVWS channelcompletely and start a new ‘Discover’ and ‘Request’ process. The primaryuser can never be affected by a ‘Trim’ message.

‘Queue Propose’: The ‘Queue Propose’ message can be integrated into‘TVWS Info’ or ‘Revoke’ messages. The spectrum server 28 stores the‘TVWS Filter’ of a client and offers him a place in the dynamic whitespace database queue. The client can accept this offer by sending a‘Queue Confirm’ message.

‘TVWS Push’: As soon as the spectrum server 28 finds appropriate TVWSchannels matching the ‘TVWS Filter’ of a client waiting in the dynamicwhite space database queue, the client is informed by means of the ‘TVWSPush’ message. A WSD that receives such a message can omit a ‘Discover’process and directly request the offered TVWS. The ‘TVWS Filter’ canthereby be altered, but there is a risk of not matching a principallyavailable TVWS channel anymore and getting a ‘Reject’ message instead.

‘Spectrum Demand’: The decision logic 14′ of the dynamic broadcastnetwork regularly receives ‘Spectrum Demand’ messages from the spectrumserver 28. Therein, summarized secondary spectrum demand metrics aretransferred. The decision logic 14′ takes these metrics intoconsideration when calculating the dynamic broadcast content deliveryscheduling. A regular exchange between the spectrum server 28 and thedecision logic 14′ makes sure that the TV spectrum is efficientlyutilized and dynamic TVWS are available at the demanded time.

The following example that is basically illustrated in FIG. 15 explainsthe communication protocol between the spectrum server 28 and two WSDs,one of which has a higher priority. The higher priority spectrum usermight as well be the dynamic broadcast network. For illustrationpurposes this case is deliberately ignored, since it would result in amuch easier example.

First, WSD 1 successfully requests a TVWS channel and immediately startsto use it. After a while WSD 2, which has a higher priority, decides touse a TVWS channel which is in conflict with the channel used by WSD 1.The spectrum server 28 sends a ‘Trim’ or a ‘Revoke’ message to WSD 1,respectively. During the fadeout time, which is as long as therecommended waiting time for WSD 2, WSD 1 already tries to find anotherTVWS channel by sending a ‘Discover’ message. It only receives an emptyTVWS list and confirms the proposed place in the dynamic white spacedatabase queue (‘Queue Propose’/‘Queue Confirm’). After WSD 2 releasesits TVWS channel, the spectrum server 28 informs WSD 1 about anappropriate TVWS channel by means of a push message. Later, WSD 2requests a TVWS channel which is not in conflict with the TVWS channelof WSD 1. Hence, both spectrum users can use available TVWS spectrumsimultaneously.

Dynamic broadcast introduces a new way to use the scarce terrestrialspectrum more efficiently. This is achieved by the co-working ofbroadcast and broadband networks, and particularly the user terminals.Being capable to access to both networks and equipped with a storagedevice user terminals become an active and important component of thesystem.

The benefits of dynamic broadcast can be enormous: For the broadcasterand the operator of broadcast networks the network cost can be reducedand/or more capacity on the same network (“virtual channels”, i.e.channels which are traditionally used for broadcasting predeterminedcontent according to a predetermined schedule, but which are now freefor use by other services or transmission of other content since saidpredetermined content is broadcast earlier for storage in the terminalor is transmitted via a broadband network) can be generated withoutincrease in spectrum and cost. The usage of the created “White Spaces”will be organized in a broadcaster-controlled fashion. Moreover this isan elegant way to avoid the proliferation of inflexible “DigitalDividends”. For the operator of broadband networks, it may be possibleto reduce the peak traffic in times where popular programs arebroadcasted. For the operators of cellular networks and Wi-Fi, and otherwireless communication networks, additional spectrum resources will bemade available. And conflicts with broadcasters and the public as aresult of unmanaged/uncontrolled interference can also be avoided. Forthe regulator, this is a way to prevent conflicts between operators ofcellular networks and broadcasters, and to ease the problems occurringas a result of the use of “White Spaces”. It can be seen as a smoothpath towards a next “Digital Dividend”.

In contrast to today's TV sets, user terminals become active networkcomponents, which are capable of accessing both networks, and which areequipped with a storage device in order to support the various deliverymechanisms of a dynamic broadcast system. Based on monitoring andsignaling data linear TV services need to be built up directly insidethe terminals. Network initiated switching operations and also recordingand playback functionalities, which are required to fulfill this task,have been introduced.

A terminal generally allows receiving the same TV service via broadcast(DVB-T) and broadband (UDP/IP) in parallel. Based on the assumption thatequivalent A/V can be received via either way and that these data aredelivered as payload of MPEG-2 TS packets the sync process required forseamless switching between the transmission channels had been developed.

In the end it is worth pointing out that dynamic broadcast is notrestricted to terrestrial broadcast networks but can also be deployed incable or, generally, any other broadcast networks. Further, thebroadband network can generally be any (wired or wireless) broadbandnetwork, such as an internet, IP, computer or communications network.The terminal may be stationary or portable (e.g. part of a a mobilephone, PDA or tablet PC) device and may generally use any datatransmission protocol. Further, the terminal may be incorporated into ahome gateway, such as a broadband router, and may include broadcastreceivers for a whole domicile or building. Still further, the terminalmay be included into a Femtocell. Still further, the terminal, theelements of the broadcast system and the control device are not limitedto the embodiments shown and explained herein. For instance, theterminal may comprise two or more broadcast receivers (of the same typeor of different type, e.g. to receive broadcast content from differentbroadcast networks) and/or two or more broadband receivers (of the sametype or of different type, e.g. to receive broadband content fromdifferent broadband networks).

Obviously, numerous modifications and variations of the presentdisclosure are possible in light of the above teachings. It is thereforeto be understood that within the scope of the appended claims, thepresent disclosure may be practiced otherwise than as specificallydescribed herein.

In the claims, the word “comprising” does not exclude other elements orsteps, and the indefinite article “a” or “an” does not exclude aplurality. A single element or other unit may fulfill the functions ofseveral items recited in the claims. The mere fact that certain measuresare recited in mutually different dependent claims does not indicatethat a combination of these measures cannot be used to advantage.

In so far as embodiments of the present disclosure have been describedas being implemented, at least in part, by software-controlled dataprocessing apparatus, it will be appreciated that a non-transitorymachine-readable medium carrying such software, such as an optical disk,a magnetic disk, semiconductor memory or the like, is also considered torepresent an embodiment of the present disclosure. Further, such asoftware may also be distributed in other forms, such as via theInternet or other wired or wireless telecommunication systems.

1. (canceled)
 2. A device for allocating frequency resources toterminals, the device comprising: circuitry configured to allocate thefrequency resources between broadcast services and wireless broadbandservices in a defined group of frequencies; store and update a databaseof allocated frequency resources and of white spaces in the definedgroup of frequencies; manage frequency resources that are included inthe database for access by one or more terminal devices that make use ofthe frequency resources that are included in the database, the terminaldevices being put in a white space database queue when no frequencyresources are available to match a request; revoke one of the frequencyresources granted to one or more of the terminal devices based on arevoke message; send a queue propose message to the one or more of theterminal devices from which said one of the frequency resources wasrevoked, offering to put the one or more of the terminal devices on thedatabase queue; determine whether a queue confirm message is receivedfrom said one or more of the terminal devices in response to the queuepropose message, the queue confirm message indicating how long said oneor more of the white space devices is willing to wait in the databasequeue; and if the queue confirm message is received from said one ormore of the terminal devices in response to the queue propose message,put the one or more of the terminal devices in the database queue. 3.The device according to claim 2, wherein the queue propose messagerelates to a queue for the frequency resources revoked.
 4. The deviceaccording to claim 2, wherein the queue propose message relates to aqueue for the frequency resources that match a filter which include therevoked frequency resources.
 5. The device according to claim 2, whereinthe circuitry is further configured to send information relating toalternative frequency resources to the frequency resources that are tobe revoked.
 6. The device according to claim 5, wherein the circuitry isconfigured to send the information relating to the alternative frequencyresources to the frequency resources that are to be revoked in responseto the request from the one or more terminal devices.
 7. The deviceaccording to claim 5, wherein the circuitry is configured to send theinformation relating to the alternative frequency resources to thefrequency resources that are to be revoked if the queue confirm messageis not received from said one or more of the terminal devices.
 8. Thedevice according to claim 2, wherein the revoke message indicates thefrequency resources to be revoked at a time in the future.
 9. The deviceaccording to claim 2, wherein the frequency resources comprise frequencyresources for cellular network data transmission.
 10. The deviceaccording to claim 2, wherein the frequency resources comprise frequencyresources for wi-fi network data transmission.
 11. The device accordingto claim 2, wherein the broadcast services use unidirectionaltransmissions and the wireless broadband services use bidirectionalnetwork.
 12. The device according to claim 2, wherein the white spacesare unallocated frequencies but that are allocatable by the device. 13.The device according to claim 2, wherein the revoking is based on aprioritization level for the service.
 14. The device according to claim2, wherein the allocating is based on at least one of geographicallocation and transmit power.
 15. The device according to claim 2,wherein the allocating is based on time information and geographicallocation information.
 16. A method for allocating frequency resources toterminals, the method comprising: allocating, using circuitry, thefrequency resources between broadcast services and wireless broadbandservices in a defined group of frequencies; storing and updating, usingthe circuitry, a database of allocated frequency resources and of whitespaces in the defined group of frequencies; managing, using thecircuitry, frequency resources that are included in the database foraccess by one or more terminal devices that make use of the frequencyresources that are included in the database, the terminal devices beingput in a white space database queue when no frequency resources areavailable to match a request; revoking, using the circuitry, one of thefrequency resources granted to one or more of the terminal devices basedon a revoke message; sending, using the circuitry, a queue proposemessage to the one or more of the terminal devices from which said oneof the frequency resources was revoked, offering to put the one or moreof the terminal devices on the database queue; determining, using thecircuitry, whether a queue confirm message is received from said one ormore of the terminal devices in response to the queue propose message,the queue confirm message indicating how long said one or more of thewhite space devices is willing to wait in the database queue; and if thequeue confirm message is received from said one or more of the terminaldevices in response to the queue propose message, putting, using thecircuitry, the one or more of the terminal devices in the databasequeue.
 17. The method according to claim 16, wherein the queue proposemessage relates to a queue for the frequency resources revoked.
 18. Themethod according to claim 16, comprising sending, using the circuitry,information relating to alternative frequency resources to the frequencyresources that are to be revoked.
 19. A non-transitory computer-readablemedium having instructions stored thereon that, when carried out on acomputing device, cause the computing device to perform a methodcomprising: allocating the frequency resources between broadcastservices and wireless broadband services in a defined group offrequencies; storing and updating a database of allocated frequencyresources and of white spaces in the defined group of frequencies;managing frequency resources that are included in the database foraccess by one or more terminal devices that make use of the frequencyresources that are included in the database, the terminal devices beingput in a white space database queue when no frequency resources areavailable to match a request; revoking one of the frequency resourcesgranted to one or more of the terminal devices based on a revokemessage; sending a queue propose message to the one or more of theterminal devices from which said one of the frequency resources wasrevoked, offering to put the one or more of the terminal devices on thedatabase queue; determining whether a queue confirm message is receivedfrom said one or more of the terminal devices in response to the queuepropose message, the queue confirm message indicating how long said oneor more of the white space devices is willing to wait in the databasequeue; and if the queue confirm message is received from said one ormore of the terminal devices in response to the queue propose message,putting the one or more of the terminal devices in the database queue.